Bearing metal alloy



Patented Sept. 29, 1936 UNITED STATES 2,055,740 BEARING METAL ALLOY Rowland Thomas Dryll Williams, New Town,

Hobart, Tasmania, and Alan Stewart Gill, Hobart, Tasmania, Australia No Drawing.

Application November 12, 1935,

Serial No. 49,440. In Australia November 14,

2 Claims.

This invention relates to improvements in bearing metal alloys and refers especially to bearing metal alloys having cadmium as the major constituent.

Bearing metal alloys of this type commonly contain a small proportion of copper and the composition of one known bearing metal alloy is approximately 97.5% cadmium, 1.5% copper, together with 1.0% magnesium. It has been found that under certain conditions bearing metal of this composition becomes embrittled with age. This embrittlement is probably due to a change of structure of the matrix from the eutectic type to a stable neutral single constituent type. This change appears to be accelerated by internal stresses and high working temperatures, and conditions may therefore be such that embrittlement occurs very slowly, and even the fully embrittled alloy may give satisfactory service under some conditions. The stable form of the alloy, however, is too brittle for use as a bearing metal under severe conditions.

We have discovered that this matrix modification and embrittlement may be greatly reduced by decreasing the magnesium content of the al loy, and that if the magnesium content is reduced to the region of 0.1% or less, embrittlement and structure change of the alloy with age are almost entirely avoided.

It has been found, however, that if the magnesium content is made as small as 0.1% and the copper content remains as before-i. e. at l.5%- the resulting alloy has insufficient strength to withstand the shrinkage stresses when used in a bonded bearing, and that radial cracks may develop as a result of this weakness.

One object of the invention, therefore, is to provide a bearing metal alloy containing cadmium as the major constituent, which will be substantially free from embrittlement on ageing and yet will possess sufficient strength to withstand the heavy shrinkage stresses developed in bonded bearings.

The invention is directed to the use of silver in a bearing metal alloy, and more particularly to the use of that element in an alloy having cadmium as its major constituent and contain ing small proportions of copper and magnesium. The proportion of silver is kept sufficiently low to permit of the alloy retaining the typical bearing metal microstructure.

Bearing metal alloys in accordance with the invention consist preferably of cadmium, copper, magnesium and silver, the magnesium being in such proportion that the alloy has little tendency to become embrittled with age, and the copper and silver contents being adjusted so that the desired bearing metal microstructure of the alloy is produced, while, at the same time, the alloy is given the desired physical characteristics of strength, ductility, hardness, and freedom from embrittlement.

For this purpose the proportion of copper is preferably in the region of 1% to 2%, the proportion of magnesium is preferably in the region of 0.01% to 0.15% and the proportion of silver is preferably in the region of 0.05% to 0.5%.

One example of an alloy produced according to this invention has the following approximate composition:

Example Percent Cadmium 98.2 Copper 1.45 Magnesium Silver One method of manufacture of this alloy according to this invention, which has been found satisfactory, comprises melting the cadmium and adding the copper and silver when the cadmium is at a temperature of approximately 380-400" 0., and after these have dissolved, adding the magnesium in the required proportion.

However, it will be clear that this method of manufacture of the alloy is only one of many which may be satisfactorily employed, and it is to be understood, therefore, that this method is given only by way of example and it is not to be regarded as limitative.

Moreover, it will be appreciated that the proportions of the various elements given above may be varied while retaining desired properties in the resulting alloy, and we therefore do not wish to be understood as limiting ourselves by the precise terms and proportions set out in the above description except in such manner as the state of the art may require.

We claim:

1. A bearing metal alloy comprising 1% to 2% copper, 0.01% to 0.15% magnesium, 0.05% to 0.5% silver, and the balance cadmium.

2. A hearing metal alloy comprising the following elements in substantially the proportions given:

Percent Cadmium 98.2 Copper 1.45 Magnesium 0.10 Silver 0.25 ROWLAND THOMAS DRYLL WILLIAMS. ALAN STEWART GILL. 

